P0421 Mazda 626 1999 P0171

Hi
I have Mazda 1999 626, stated showing up code P0171. Showed it to sears Auto shop, they checked air filter, oil filter, then cleaning up of EGR Valve. Cleaning up of EGR Valve started triggering two more codes, along with P 0171. New codes p0141 abd p0421. As per the code p0141, O2 sensor Bank1 Sensor 2 was replaced (Post cat??)
. But Still code p0171 and p0421 remained. At last vacuum leak was found in take gasket and fixed . p0171 gone away, but p0421 stayed and not going away...

I see some padle stall or lazyness some time. P 0421 will come back each time you reset.

I help in his would be greatly appreciated.